Warp tension equalizer for power looms



May 25, 1954 c. DILL 2,679,266

WARP TENSION EQUALIZER FOR POWER L OOMS Filed June 24, 1953 Fie. 1

INVENTOR C19 de Dill ATTORNEY Patented May 25, 1954 2,79,265 FF I CE Clyde Dill, Greenville, S. (3., assignor to Dill Loom Adapters, Inc, of South Carolina Greenville, S.

0., a corporation Application June 24, 1953, Serial No. 363,778

17 Claims.

This invention relates to an attachment for power looms. While it is shown and described herein as applied to a Dobby loom, the broad idea is not so limited and will find application throughout the power loom art.

When using Dobby looms in the weaving, particularly of twill fabrics, a surprisingly large percentage of the woven textiles which must be graded as seconds are so graded because of an imperfection in the cloth which is known to the trade as set marks. i'he cause of set marks, which has lon been known, is the stretching of the warp yarns, which occurs whenever the loom must be stopped for any reason. The conventional modern loom includes means for automaticahy stopping the loom at any predetermined point in the weaving cycle. Generally, electrical means such as the conventional drop wires are used and the stop point enerally selected is one which allows the weaver to most easily replace a broken warp or filling yarn. The particular stop means employed forms no part of the instant invention, since it will operate satisiactorily without reference to the particular stop means employed. Particularly in weaves of the twill type, regardless of the selected stop point, whenever a loom is stopped one or more of the harnesses will always b down, while the remainder will be in a cross-over position which corresponds substantially to a closed shed position. This relationshi holds by reason of the fact that it is standard practice with weavers to set the crossin point of the harness to occur simultaneously with the stop point of the loom. Under these circumstances, those yarns which are pulled down by the harnesses in the lower position are under more tension and therefore are stretched further than are the yarns carried by the harnesses which are in the cross-over position. When the loom is stationary for a period of time sulhcient, for example, for the weaver to replace a broken warp or filling yarn, this unequalized tension between the upper and lower sheds results in such elongation of the affected yarns that the loom is again started up, imperfections known as set marks invariably appear.

Many remedies for this problem have been sought in the past suggestions have been made to equalize the tension, for example, by raising or lowering the loom whip roll and nutting bar so as to put equal strain on top and bottom sheds. However, due to the fact that the harness cords are apt to stretch or the loom may not stop in the same position each time, or any one of a dozen other things can easily happen to prevent equalized tension on the upper and lower sheds. For these reasons, weave room men have long sought a mechanical means of taking the strain off both upper and lower sheds when the loom stops. Heretofore, they have attempted such schemes as letting back a certain numher of teeth on the take up gear, which in effect allows the cloth to slack towards the back of the loom.

the whip roll forenjoyed substantial involve a manual due to the human the invention comprises raising all of the har nesses to the same or substantially the same level. Originally, the apparatus of this invention was so organized that it was activated only upon the stopping of the loom. In its present form, however, the device operates once on every pick as well as on each automatic stop. Broadly therefore, the invention comprehends an attachment for a loom which will operate on at least every other automatic stop to level or substantially level all harnesses. It has been found that by so doing, not only will set marks be largely eliminated, but also the breakage of warp threads due to tension in the lower sheds is also greatly minimized.

Accordingly, it is the primary object of the instant invention to provide an attachment for a loom which will substantially eliminate set marks.

It is a further object of this invention to pro-.

for a loom which will miniwarp threads.

vide an attachment mize the breaking of It is also an object of the present invention.

to provide a simple, inexpensive device which is easily attached, for example, to the head of a Dobby loom to achieve the above objects.

A still further object of the present invention is to provide an attachment for a loom which will equalize tension on the upper and lower sheds not only in response to the stopping of a loom due to a warp or filling break, but which will also equalize tension in the same sheds once on each pick of the loom cycle.

Other objects will be apparent from the following description taken in conjunction with the attached drawings, in which:

Figure 1 is a perspective view of portions of '2.

Bobby head with th instant invention applied thereto;

Figure 2 is a top invention; and

Figure 3 illustrates in part a modification of the device shown in Figures 1 and 2.

Referring now to Figure 1, there is shown a Dobby head frame ll together with the ground harness jacks ii, the back Debby rocker arm l3 and a single set of harness straps i i. The appaplan view or portions of this ratus involved in the instant invention includes shaft Hi rotatably mounted in a pair of bearing members it and ll. The latter are bolted or otherwise rigidly attached to points on the front and rear of the Bobby head.

It has also been suggested that warp, tension be relieved toward the front of the loom pick of the loom cycle and/or on each corresponding- 0 Rigidly attached to shaft l5 and extending radially therefrom in parallel relation to each other are a pair of arms l8 and i9.

20. A substantially U -shaped'stirrup member 2 5, having openings in the ends of its arms to receive shaft 29, is pivotally mounted thereon. The Size of the stirrup member is dictated by the number of working ground harness jacks. Fig;- ure 1 shows six such jacks (whichxis the murals-er: used in weaving a two-and-one twill) and the stirrup member is large enough to enclose these. On the rear end of shaft i5 there is mounted crank arm-orlever 22'. Adjustably mounted on this leveris a-cam follower 23 which may comprise" a rotary bearing. While any convenient adjustableimeans. could be used, the follower 23 is shown as mounted on the lever 22.1w of a-simple bolt2 l and nut 25. The bolt 24 extends through a slot 26 in the lever 22 so that the follower 23 imay be positioned at any point within the slot. The driving means for the above de scribed: assembly comprises essentially a cam. member-21, which is bolted or otherwise suitably rigidly: attached to the back Dobby rocker arm I E as shown.

Inoperation,

rocker arm cause therefore, oscillations of the the cam 2-1 to rock the shaft ls in itsbearings lfi'and H as the follower 23' rides-back-and forth over the cam 21. The rock mg -motion of the shaft Iii causes a horizontal reciprocation of the stirrup member 2%, which results-in applying a pulling or lifting force to the ground harness jacks l2 with each pick of the loom.-

The operation of the above device is such as to bring all of the harnesses to the same or at least' substantially the same level once each pick. This is important as herein described in the weaving, for example, of twill fabrics, and particularly oi the so-called two-and-one twill as at least one-harnesswould normally be in a lowered position at all times. With the addition of the apparatus of this invention, however, there is one point on each pick at which all the harnes pulledtosubstantially the same level by means of the-stirrup member 2i. This results first of all in reducing the number ofwarp yarn breakages since'it relievesduring at least'a portion of each pick, the tension on these yarns. In order that whenever the loom is stopped due to either a warp or 'filling'break the tension in the upper andlower sheds may be equalized, the timing of the-operation of this attachment is adjusted as follows. The loom is first set to' stop at any convenient point, say, for example, with the lay anywhere from about one-eighth inch up to two inches back from the fell of the cloth. The exact setting ofthe stop is not too critical and in fact, speaking in terms of bottom center and front center of the crankshaft, the stop point could be set to occur almost anywhere between these two points. Once the stop point has been determined, however, and the loom stopped in the desiredposition, the follower 23 is then adjusted in theslot 26 so that. it rests squarely upon the high point of the. cam 21. Whenever a stop occurs, therefore, the stirrup member 2! is automatically positioned to raise the normally lowered harness to the. same or substantially the same. level as. the upper. or crossing harness. When'the loom has totremainat rest for any period of time, such, for example, as the time required to replace axbrokenwarp. or filling yarn,

The outer ends of these arms are joined-bye second shaft.

- stirrup. member the tension. on the upper and lower sheds is sufiiciently equalized to prevent stretching, which isrthe major cause of set marks.

Referring now to Figure 3 of the attached sheetofdrawings, there is shown a modification of this apparatus which, while similar in function, has a somewhat different structural configuration. The. same driving means may be used and the principal difference lies in replacing the 2 i with a plurality of false jacks 3|. There will be one of these false jacks for each of the regular ground harness jacks and each will be pivoted to; the upper end of the regularzjacks as shown. The lower end ofeach of the ialse-jacksis connected to the shaft -20 by means ofya. chain or other non-rigid member. 322. The-harness strapsM in thiscase are driven" by the false jacks'rather-than by-the regular: jacks and-once each-pick the false jack-members are ,pivotedabout their upper ends by means of J the chains Bi-so thatas-before, all harnesses. are. broughtrto substantially the samelevelonce on eachlpickuand also. whenever the 100m is automatically stopped :due to a warp or filling break;

The; drive means encompassed in" the attache ment Ofe'thiS invention is shown and described as" including a, cam member attached'to theback Dobby rocker arm. Whil'ethis provides a simple means'for obtainingpower. and for timingythe action of. the attachment with respect to the weaving cycle of the loom; itwill be obvious that the drive and timing couldrjust aswell be taken from anumber of. other-points on the loom proper; For-examplathe.drive could be-taken from the whip roll follower. arm or from thepattern' drumworm shaft; In-. addition, the apps. ratus=zmay be. set up.to operate once each pick, oncexevery other pick and/ or. only uponan all-- tomatic stopdue to a warp or filling break. In the latter case. simple solenoid connected in' paralleliwiththe automatic stop circuiticould be usedto rock the shaft I 5.

Fromxtheforegoingit will be apparent to those skilled in'the art of weaving that'there is shown and" described herein a new and useful device whichwill have many equivalents within the scope. of the appended :claims.

1' claim:

1'. Incombination witha loom having means for automatically stopping at a predetermined; point of the weaving cycle on warp and filling breaks. a device for equalizing tension on the upper andtlower warp sheds, said device comprising: means for positively bringing all ground harnesses to substantially the same level; and means operatively associated with said first mentioned'imeans and operating in timed relation to the loom-motion for'actuating said'first mentioned means during said loom motion and whenever the loom is automatically stopped by a-warp or. fillingbreak.

2. In combination with a loom having means for automatically stopping at a predetermined point of the weaving cycle on warp and filling breaks; a device for equalizing tension on the upperand lower warp sheds, said device comprising: means for-positively bringing all ground harnessesto substantially the same level; and means operatlvcly associatedwith said first mentioned means and operating in timed relation to the'stopmotion of the loom for actuating saidfirsh mentioned means whenever the loom is: automatically stopped by either a warp or filling break.

3; In combination with a: Dobby loom having:

means for stopping at a predetermined point of the weaving cycle on warp and filling breaks, a device for equalizing tension on the upper and lower warp sheds, said device comprising: means for positively bringing all ground harnesses to substantially the same level; and means operatively associated with said first mentioned means and operating in timed relation to the loom motion for operating said first mentioned means during said loom motion and whenever the loom is automatically stopped by a warp or filling break.

4. A loom as defined by claim 3 in which the predetermined stop point of the loom corresponds to the point of operation on each pick of the tension equalizing device.

5. In combination with a Dobby loom, a device for equalizing tension on the upper and lower warp sheds, said device comprising: means positioned adjacent to and operatively associated with the ground harness jacks; and means driven by the loom motion and operating in timed relation thereto for actuating said first mentioned means to positively move said jacks to substantially level all ground harnesses during said loom motion.

6. In combination with a Dobby loom, a device for equalizing tension on the upper and lower warp sheds, said device comprising: a substantially U-shaped stirrup member pivotally mounted with respect to the loom frame and surrounding the ground harness jacks, the open end of the U facing the pattern drum end of the loom; and mechanical means for reciprocating said member in the plane of movement of the jacks to exert a pulling force on those jacks connected to lowered harnesses, said means operating in timed relation to the loom motion so that all harnesses are automatically levelled during said loom motion.

7. A device as defined by claim 5 which is operative to level the harness once on each pick.

8. A device as defined by claim 6 which is operative to level the harness once on each pick.

9. In combination with a Dobby loom, a device for substantially equalizing tension on the upper and lower warp sheds, said device comprising: a shaft revolubly mounted on the Dobby head and positioned to extend from front to back thereof, adjacent that side of the jacks which is remote from the harnesses; a pair of arms rigidly mounted on said shaft and extending radially therefrom in substantially parallel relation to each other; means pivotally connected to the outer ends of said arms and extending therefrom to surround the ground harness jacks; cam means positioned on the back Dobby rocker arm; and follower means connected to said shaft and bearing on said cam means to rotate said shaft alternately in opposite directions to cause all harnesses to level on each pick.

10. In combination with a Dobby loom, a device for automatically equalizing tension on the upper and lower warp sheds whenever the loom stops due to warp or filling breaks, said device comprising: means mounted on the loom for positively moving the ground harness jacks into substantially front to back alignment; and means operatively associated with said first mentioned means and operating in timed relation to the loom motion for automatically causing operation of said first mentioned means whenever the loom stops on a warp or filling break; whereby all groiuid harnesses are brought to substantially the same level Whenever the 100m stops due to a warp or filling break.

11. The combination defined by claim 10 in which the first mentioned means includes a member having a straight surface for engaging the edges of the jacks which are opposite the notched edges, said member being mounted for reciprocatory motion on the Dobby head.

12. The combination defined by claim 10 in which the second mentioned means includes a cam member rigidly attached to the back Dobby rocker arm.

13. In combination with a Dobby loom, a device for substantially equalizing tension on the upper and lower warp sheds, said device comprising: a plurality of false jacks, one pivotally mounted to the upper edge of each of the ground harness jacks; a shaft revolubly mounted on the Dobby head and positioned to extend from front to back thereof adjacent that side of the jacks remote from the harnesses; means rigidly mounted on said shaft and extending radially therefrom; a plurality of non-rigid connectors one connected between the lower portion of each of said false jacks and said means; and further means operatively connected to said shaft and driven by the loom motion for oscillating said shaft to pull all ground harnesses to substantially the same level once every pick and whenever the loom is automatically stopped on a warp or filling break.

14. The combination defined by claim 13 in which the first mentioned means comprises a pair of arms extending radially from said shaft in parallel relation thereto and a second shaft connecting the outer ends of said arms and said second mentioned means includes a cam rigidly attached to the back Dobby rocker arm and a lever rigidly connected to the shaft and having follower means thereon adapted to bear on said cam.

15. A device for attachment to the head of a Dobby loom comprising in combination: a pair of bearing members for attachment to opposite sides, front and rear, of a Dobby head; a shaft for rotative mounting in said bearings; a pair of arms rigidly attached to said shaft and extending radially therefrom in substantially parallel relation to each other; a substantially U-shaped stirrup member pivotally mounted at the ends of its legs to the outer ends of said arms; a lever rigidly attached to said shaft; cam follower means mounted on said lever; and a cam member for attachment to the back Dobby drive arm.

16. In combination with a loom having means for automatically stopping at a predetermined point of the weaving cycle on warp and filling breaks, a device for equalizing tension on the upper and lower warp sheds, said device comprising: means for positively bringing all ground harnesses to substantially the same level; and means operatively associated with said first mentioned means and operating in timed cyclic relation with insertion of the picks for actuating said first mentioned means.

17. The combination defined by claim 1 in which the frequency of operation of said device is once each pick.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 488,286 Risk Dec. 20, 1892 512,172 Ehrenberg Jan. 2, 1894 701,683 Cowan June 3, 1902 871,398 Gordon, Jr. Nov. 19, 1907 

